The present disclosure relates generally to Fresnel antennas.
Antennae for receiving light are important in electronic imaging and energy conversion. Electronic imaging involves converting electromagnetic waves to electrical signals, thereby allowing the image to be stored, analyzed, or reproduced electronically. Some current electronic imaging devices are used in, e.g., digital cameras, infrared cameras, microscopes, night vision goggles and document scanners. Energy conversion relates to solar power cells that convert light energy to electrical energy.
Fresnel lenses have been used in optics to capture light and direct it to photo detectors. Fresnel lenses, however, have had a lower limit on the size of the Fresnel elements because the spacing between the elements had to be large enough to interact with, and direct light waves to photo detectors.
Recent advances in subwavelength optics have been achieved using nanometer scale metal structures to convert light to surface plasmons. Periodic structures surrounding a subwavelength aperture on the entrance and exit side of the aperture have allowed the transmission of a well defined beam “through” the subwavelength aperture.